UTILIZING SURVEY GRADE GPS & WAVE OBSERVATIONS TO MONITOR SHORT TERM LITTORAL SEDIMENTS ALONG OUTER CAPE COD MASSACHUSETTS

Background/Objective:

The objective of the work is to estimate the amount of sediment loss and gain at selected locations within outer Cape Cod. Comparing beach profiles taken this year to previous profiles, LIDAR, and historic data provides clues to the amount of loss or gain. With beach profile data we have considered wave (2004) and weather data (2002) from recent years. The wave data highlights the dominant transport direction. Wave period generally divides their origin whether from the Gulf of Maine waves or ocean waves from beyond George’s Bank. The weather data will assist in showing storm wave events. These three data sets highlight some of the drivers and outcomes of recent coastal change for outer Cape Cod.

Methods:

Several different data sets were collected and used to complete this study. They are as follows:

Beach Profiles: Utilizing a Trimble RTK and base station, we conducted continuous topographic surveys perpendicular to the beach at a number of sites on Cape Cod. There are five to six lines per each of the 12 sites. Starting at the dune toe we collected elevations at 1-meter intervals until we reached the water edge. These points consisted of a UTM coordinate with vertical and horizontal control. Vertical accuracy is estimated between 2-4 cm. Profiles collected during the 2014 season will be compared to previous beach profile and LIDAR dating back to 2010.

Wave Data- Observations were collected every other day by the Provincetown Center for Coastal Studies (PCCS) volunteers over ten years since 2004. An observer notes series of waves for their period, amplitude, wavelength, and wave angle.

Weather Data- Data were acquired from the National Oceanic Atmospheric Administrations (NOAA), National Data Buoy Center (NDBC). Station 44018 has been recording data since 2002. We will look for changes in the wave intensity over the selected time period.

Expected Results:

• Create baseline data for comparison in future years.
• From surveying standpoint we will better the methods for conducting beach profiles.
• With profiles we can calculate sediment volume change compared to the 2010 LIDAR data.

Conclusion:

From the use of technology and new tools like that of survey grade GPS, and LIDAR, coastal scientists at Cape Cod National Seashore are able to assess short term and long term coastal change and estimate the coastal vulnerability.